Here we have used the notation \(\phi ^{a}\equiv \epsilon ^{a}(\phi _{1},\phi _{2})^{t}\)  and the identity
\(\epsilon ^{a}\epsilon ^{a}=1\) . Note that the probability density \(\rho \)  is positive definite in our model. We emphasize that the quantities \(\rho \)  and \(\vec{J}\)  in (REF ) are physically well defined to yield a good quantization, similar to the Dirac RQM for the massive electron with spin 1/2 described by the four component wave function
\(\psi =(\psi _{u},\psi _{d})^{t}\) , where the corresponding probability density
\(\rho _{D}=\psi _{u}^{\dagger }\psi _{u}+\psi _{d}^{\dagger }\psi _{d}\)  is
also positive definite. However, in the Klein-Gordon model, the probability density \(\rho _{KG}\)  for the relativistic spinless boson is not positive definite [1]}.
